Currently, in X-ray image diagnosis, an absorption image that images attenuation of an X-ray after passing through an object is used. On the other hand, since X-rays are a type of electromagnetic waves, attention is paid to this wave nature, and attempts to image changes in the phase after X-rays have passed through an object have been made in recent years. These are called an absorption contrast and a phase contrast, respectively. The imaging technique using such a phase contrast is considered to have a high sensitivity to soft tissues of a human body containing a lot of these because the sensitivity to light elements is higher than a conventional absorption contrast.
However, since a conventional phase contrast imaging technique needs the use of a synchrotron X-ray source or a minute focus X-ray tube, it has thought to be difficult for them to be in practical use in general medical facilities because the former needs to have a huge facility and the latter cannot secure sufficient X-ray dose to photograph a human body.
In order to solve this problem, X-ray image diagnosis (Talbot system) using an X-ray Talbot-Lau interferometer capable of acquiring a phase contrast image using an X-ray source conventionally used in a medical field is expected.
As shown in FIG. 2, a Talbot-Lau interferometer has a G0 lattice, a G1 lattice, and a G2 lattice each disposed between a medical X-ray tube and an FPD, and visualizes refraction of X-rays by a subject as moire fringes. X-rays are irradiated in a longitudinal direction from an X-ray source disposed in an upper portion and reach an image detector through G0 lattice, subject, G1 lattice, and G2 lattice.
As a manufacturing method of a lattice, for example, a method is known in which a silicon wafer having high X-ray transmissivity is etched to provide lattice-shaped recesses and heavy metals having high X-ray shielding properties are filled therein.
However, with the above method, it is difficult to increase the area due to available silicon wafer size, etching apparatus restriction, or the like, and an object to be photographed is limited to a small part. It is not easy to form a deep recess in a silicon wafer by etching, and it is also difficult to evenly fill metal to the bottom of the recess, and therefore, it is difficult to fabricate a lattice having a thickness enough to sufficiently shield X-rays. For this reason, particularly under high-voltage photographing conditions, X-rays penetrate the lattice, making it incapable of obtaining a favorable image.
On the other hand, it is also studied to adopt a lattice-shaped scintillator having a lattice function added to a scintillator constituting an image detector.